The present invention is equally applicable to transmitters, receivers, and transceivers. It will find wide application in many environments. One such environment is the cell phone operating in the 900 MHz range but is applicable to all cell phone bands. It is necessary to regulate power transmitted by a cell phone to avoid interference with adjacent channels and comply with standards. One such standard is Mobile Station-Base Station Compatibility Standard for Dual-Mode Wide Band Spread Spectrum Cellular System, EIA/TIA Interim Standard IS-95, Telecommunications Industry Association, Washington, D.C., 1993.
Prior art circuits comprising RF signal circuit elements typically use multiple processing stages, including amplification of RF signal before the signal reaches the antenna where it is transmitted. In a typical transmitter of a direct conversion cell phone transceiver, normally comprises a digital to analog converter, a filtering stage and IQ (in-phase and quadrature) modulator, a filtering stage, a power amplifier, and another filter. Commonly, an automatic gain control function is applied to the final amplifier stage. Complex digital and analog circuitry in the cell phone regulate the strength of the transmitted signal and the receive signal level at the baseband processor.
Input and output impedances of the final amplifiers stage will vary. Output impedances of the modulator and the filter stage will vary. Variations in impedance can contribute to degraded signal to noise ratio and will cause various amounts of reflective power within the circuit. It is therefore desirable to provide a means and method for overcoming the aforesaid shortcomings. It is equally desirable to cure such shortcomings in input circuitry in the receiver's circuit.